Re: [PATCH v4 3/6] pseries/plpks: expose PowerVM wrapping features via the sysfs

Nayna Jain
2026-01-15T20:45:23Z

On 1/15/26 5:05 AM, Srish Srinivasan wrote:
> Starting with Power11, PowerVM supports a new feature called "Key Wrapping"
> that protects user secrets by wrapping them using a hypervisor generated
> wrapping key. The status of this feature can be read by the
> H_PKS_GET_CONFIG HCALL.
>
> Expose the Power LPAR Platform KeyStore (PLPKS) wrapping features config
> via the sysfs file /sys/firmware/plpks/config/wrapping_features.
Thanks for the patch.

Reviewed-by: Nayna Jain <nayna@linux.ibm.com>
>
> Signed-off-by: Srish Srinivasan <ssrish@linux.ibm.com>
> ---
> .../ABI/testing/sysfs-firmware-plpks | 8 ++++++++
> arch/powerpc/include/asm/hvcall.h | 4 +++-
> arch/powerpc/include/asm/plpks.h | 3 +++
> arch/powerpc/platforms/pseries/plpks-sysfs.c | 2 ++
> arch/powerpc/platforms/pseries/plpks.c | 20 +++++++++++++++++++
> 5 files changed, 36 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-firmware-plpks b/Documentation/ABI/testing/sysfs-firmware-plpks
> index af0353f34115..cba061e4eee2 100644
> --- a/Documentation/ABI/testing/sysfs-firmware-plpks
> +++ b/Documentation/ABI/testing/sysfs-firmware-plpks
> @@ -48,3 +48,11 @@ Description: Bitmask of flags indicating which algorithms the hypervisor
> supports for signed update of objects, represented as a 16 byte
> hexadecimal ASCII string. Consult the hypervisor documentation
> for what these flags mean.
> +
> +What: /sys/firmware/plpks/config/wrapping_features
> +Date: November 2025
> +Contact: Srish Srinivasan <ssrish@linux.ibm.com>
> +Description: Bitmask of the wrapping features indicating the wrapping
> + algorithms that are supported for the H_PKS_WRAP_OBJECT requests
> + , represented as a 8 byte hexadecimal ASCII string. Consult the
> + hypervisor documentation for what these flags mean.
> diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h
> index 9aef16149d92..dff90a7d7f70 100644
> --- a/arch/powerpc/include/asm/hvcall.h
> +++ b/arch/powerpc/include/asm/hvcall.h
> @@ -360,7 +360,9 @@
> #define H_GUEST_RUN_VCPU 0x480
> #define H_GUEST_COPY_MEMORY 0x484
> #define H_GUEST_DELETE 0x488
> -#define MAX_HCALL_OPCODE H_GUEST_DELETE
> +#define H_PKS_WRAP_OBJECT 0x490
> +#define H_PKS_UNWRAP_OBJECT 0x494
> +#define MAX_HCALL_OPCODE H_PKS_UNWRAP_OBJECT
>
> /* Scope args for H_SCM_UNBIND_ALL */
> #define H_UNBIND_SCOPE_ALL (0x1)
> diff --git a/arch/powerpc/include/asm/plpks.h b/arch/powerpc/include/asm/plpks.h
> index 8829a13bfda0..8f034588fdf7 100644
> --- a/arch/powerpc/include/asm/plpks.h
> +++ b/arch/powerpc/include/asm/plpks.h
> @@ -23,6 +23,7 @@
> #define PLPKS_IMMUTABLE PPC_BIT32(5) // Once written, object cannot be removed
> #define PLPKS_TRANSIENT PPC_BIT32(6) // Object does not persist through reboot
> #define PLPKS_SIGNEDUPDATE PPC_BIT32(7) // Object can only be modified by signed updates
> +#define PLPKS_WRAPPINGKEY PPC_BIT32(8) // Object contains a wrapping key
> #define PLPKS_HVPROVISIONED PPC_BIT32(28) // Hypervisor has provisioned this object
>
> // Signature algorithm flags from signed_update_algorithms
> @@ -103,6 +104,8 @@ u32 plpks_get_maxlargeobjectsize(void);
>
> u64 plpks_get_signedupdatealgorithms(void);
>
> +u64 plpks_get_wrappingfeatures(void);
> +
> u16 plpks_get_passwordlen(void);
>
> void plpks_early_init_devtree(void);
> diff --git a/arch/powerpc/platforms/pseries/plpks-sysfs.c b/arch/powerpc/platforms/pseries/plpks-sysfs.c
> index 01d526185783..c2ebcbb41ae3 100644
> --- a/arch/powerpc/platforms/pseries/plpks-sysfs.c
> +++ b/arch/powerpc/platforms/pseries/plpks-sysfs.c
> @@ -30,6 +30,7 @@ PLPKS_CONFIG_ATTR(used_space, "%u\n", plpks_get_usedspace);
> PLPKS_CONFIG_ATTR(supported_policies, "%08x\n", plpks_get_supportedpolicies);
> PLPKS_CONFIG_ATTR(signed_update_algorithms, "%016llx\n",
> plpks_get_signedupdatealgorithms);
> +PLPKS_CONFIG_ATTR(wrapping_features, "%016llx\n", plpks_get_wrappingfeatures);
>
> static const struct attribute *config_attrs[] = {
> &attr_version.attr,
> @@ -38,6 +39,7 @@ static const struct attribute *config_attrs[] = {
> &attr_used_space.attr,
> &attr_supported_policies.attr,
> &attr_signed_update_algorithms.attr,
> + &attr_wrapping_features.attr,
> NULL,
> };
>
> diff --git a/arch/powerpc/platforms/pseries/plpks.c b/arch/powerpc/platforms/pseries/plpks.c
> index 03722fabf9c3..4a08f51537c8 100644
> --- a/arch/powerpc/platforms/pseries/plpks.c
> +++ b/arch/powerpc/platforms/pseries/plpks.c
> @@ -38,6 +38,7 @@ static u32 usedspace;
> static u32 supportedpolicies;
> static u32 maxlargeobjectsize;
> static u64 signedupdatealgorithms;
> +static u64 wrappingfeatures;
>
> struct plpks_auth {
> u8 version;
> @@ -248,6 +249,7 @@ static int _plpks_get_config(void)
> __be32 supportedpolicies;
> __be32 maxlargeobjectsize;
> __be64 signedupdatealgorithms;
> + __be64 wrappingfeatures;
> u8 rsvd1[476];
> } __packed * config;
> size_t size;
> @@ -280,6 +282,7 @@ static int _plpks_get_config(void)
> supportedpolicies = be32_to_cpu(config->supportedpolicies);
> maxlargeobjectsize = be32_to_cpu(config->maxlargeobjectsize);
> signedupdatealgorithms = be64_to_cpu(config->signedupdatealgorithms);
> + wrappingfeatures = be64_to_cpu(config->wrappingfeatures);
>
> // Validate that the numbers we get back match the requirements of the spec
> if (maxpwsize < 32) {
> @@ -472,6 +475,23 @@ u64 plpks_get_signedupdatealgorithms(void)
> return signedupdatealgorithms;
> }
>
> +/**
> + * plpks_get_wrappingfeatures() - Returns a bitmask of the wrapping features
> + * supported by the hypervisor.
> + *
> + * Successful execution of the H_PKS_GET_CONFIG HCALL during initialization
> + * reads a bitmask of the wrapping features supported by the hypervisor into the
> + * file local static wrappingfeatures variable. This is valid only when the
> + * PLPKS config structure version >= 3.
> + *
> + * Return:
> + * bitmask of the wrapping features supported by the hypervisor
> + */
> +u64 plpks_get_wrappingfeatures(void)
> +{
> + return wrappingfeatures;
> +}
> +
> /**
> * plpks_get_passwordlen() - Get the length of the PLPKS password in bytes.
> *